<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
        .container {
            margin: auto;
            width: 400px;
            height: 400px;
            background-color: #aaa;
            display: flex;
            justify-content: space-around;
        }
        
        .slider {
            margin: 20px 0;
            background-color: aqua;
            display: flex;
            flex-direction: column;
            align-items: center;
        }
        
        .slider-upper {
            width: 2px;
            height: 50%;
            background-color: blueviolet;
        }
        
        .slider-middle {
            display: flex;
            width: 0;
            height: 0;
            justify-content: center;
        }
        
        .slider-middle-line {
            flex-shrink: 0;
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background-color: #fff;
            z-index: 1;
        }
        
        .slider-lower {
            flex: 1;
            width: 2px;
            background-color: black;
        }
    </style>
</head>

<body>
    <div class="container">
        <div class="slider">
            <div class="slider-upper"></div>
            <div class="slider-middle">
                <div class="slider-middle-line"></div>
            </div>
            <div class="slider-lower"></div>
        </div>
    </div>
</body>

</html>